At first, the commercial heat treater exclusively served local machine shops. Knife and tool heat treatment became a significant chunk of work in the late 1980s. But business improved dramatically in 1993 when the company not only changed its name (from Stack Heat Treaters to Stack Metallurgical Services) but received the Nadcap certification it needed to serve the aerospace industry.
In 2010, Stack purchased the largest oil-quenching vacuum carburizing furnace in North America. Designed for highly controlled heat treatment of high-precision gears, the unit can carburize and harden parts up to 70 x 70 x 80 inches and 8,000 pounds.
Today, Stack can provide the following services: endothermic gas carburizing, neutral hardening, annealing, normalizing, aluminum solution and aging (parts up to 108 inches long), ion nitriding (loads up to 5,000 pounds), stress relieving (parts up to 108 inches long and 10,000 pounds) vacuum carburizing and vacuum hardening (gas quenching up to 10 bar). The largest segment of the longtime MTI member’s business is done in its vacuum furnaces. Stack, however, is quick to credit its aluminum and endothermic processes as being vital to its success.
Stack’s aluminum heat-treat department has experienced significant growth over the past several years, going from four furnaces to 13 (six solution furnaces and seven aging ovens). Quenching can be done in water or a water-glycol mixture. Maximum furnace work zones measure 56 inches deep x by 56 inches wide x 38 inches high and 48 inches in diameter x 60 inches high. Stack has performed extensive third-party training in the processing and straightening of thin aluminum parts to provide its customers with total process capability. The company also added a walk-in freezer capable of holding aluminum product to well below -10°F.
Stack’s endothermic department has a total of 22 furnaces for hardening, carburizing, tempering, normalizing, annealing and stress relieving. The size of its furnaces range from small tooling (22 inches deep x 16 inches wide x 32 inches high) designed for a few hundred pounds to large production furnaces (72 inches deep x 36 inches wide x 30 inches high).
Stack is committed to continuous maintenance and improvement of all equipment. All older furnaces have recently been retrofitted with Super Systems Inc. (SSi) controls, providing improved repeatability and monitoring of all furnace functions.
The company is also committed to deliver heat-treated parts in the condition they were requested by the due date they were required. Stack delivers certification with all parts that reports every step of the process (times, temperatures, furnace number and all pertinent test results). The company boasts a lab that is capable of testing hardness in Brinell and all standard Rockwell scales. Stack also has microhardness equipment to inspect hardness, decarburization and case depth.
Stack Metallurgical Services is always looking to improve business. In the past year alone, the company has purchased and installed a new Solar Manufacturing 2-bar furnace and a large drop-bottom aluminum solution furnace. Stack will continue to add equipment in the future as needed to support its customers.
Visit www.stackmet.com for more information.